A heat sink having a desired and extremely high surface precision to the edge portions and a method for processing the same, which allows for stably gaining such a heat sink, are proposed in, for example, Japanese Unexamined Patent Publication 2000-22284 (Patent Document 1). This method for processing a heat sink is a method for processing a heat sink that forms a semiconductor laser element, and is characterized by having the step of forming a number of long members in rod form by cutting a member in plate form, where a first mirror surface is formed on at least one surface, the step of forming a second mirror surface by carrying out a cutting process on the upper surface of the number of members in rod form, which are secured to a jig in order to be approximately parallel to each other in a state where the first mirror surface stands approximately vertically so that an edge portion is formed between the first mirror surface and the second mirror surface, and the step of gaining a number of heat sinks by cutting the members in rod form. In addition, this method for processing a heat sink is characterized by having the step of processing one surface of a member in plate form into a mirror surface, the step of forming edge portions between the mirror surface and trenches that are created by carrying out a discharging process or a laser process on the mirror surface of the member in plate form, and the step of gaining a number of heat sinks by cutting the member in plate form along the trenches. A copper based material having excellent thermal conductivity is used as the material of this type of heat sink.    Patent Document 1: Japanese Unexamined Patent Publication 2000-22284